Methicillin-resistant staphylococcus aureus (better known as MRSA) contributed to the deaths of 5,000 people in the United States in 2013, according to the Centers for Disease Control and Prevention. The so-called “superbug” is highly resistant to conventional antibiotics because of their overuse. But when scientists in the United Kingdom recently recreated an “eye salve” found in a 10th-century medical textbook—a mixture of garlic, onion or leek, wine and oxgall (cow’s bile)—they were amazed to discover that it almost completely wiped out MRSA bacteria.

Bound in leather and held in the collections of the British Library, the 10th-century volume known as “Bald’s Leechbook” is widely considered to be one of the world’s earliest medical textbooks. According to one of its recipes, a potion of garlic, onion or leek, wine and oxgall (or bile taken from a cow’s stomach) brewed in a brass vessel can be used as an “eye salve” to treat styes and other eye infections. After Dr. Christina Lee, an Anglo-Saxon expert from the University of Nottingham, translated the recipe from the Old English, she turned to the university’s microbiology department to see if the medieval remedy would actually work.

In the laboratory, the scientists recreated the recipe according to its exact instructions, which specified leaving the mixture to stand for nine days before straining it through a cloth. They then tested its individual ingredients (including wine from a vineyard known to exist in the 9th century), the remedy itself and a control solution against large cultures of MRSA bacteria.

Each of the ingredients had been shown in previous research to have some effect on bacteria in a lab, and the researchers thought their work might show a small amount of antibiotic activity. They had little hope the remedy would prove effective against such a superbug as MRS—but they were amazed at what they found. While none of the individual ingredients had any effect, when combined according to the recipe they killed up to 90 percent of MRSA bacteria.

A facsimile of a page from "Bald's Leechbook"
A facsimile of a page from "Bald's Leechbook"

Dr. Freya Harrison of the University of Nottingham, who led the laboratory work, told the Telegraph: “We were absolutely blown away by just how effective the combination of ingredients was.” They were able to recreate the results in three more batches, made with fresh ingredients every time, and subsequent testing by collaborators in the United States (including at Texas Tech University) confirmed that the Bald’s Leechbook eye salve was more effective against MRSA bacteria than conventional antibiotic treatment.

The British team presented their research at a national microbiology conference this week. Though they warn that the results may not bear up outside the laboratory, Dr. Harrison and her colleagues are excited about the potential that they will. For her part, Dr. Lee hopes the new research will change the modern-day perception of the Middle Ages, often characterized as “the Dark Ages,” and convince us we may have something to learn from these ancient remedies. At the very least, the fact that Bald’s Leechbook and many similar textbooks contained treatments for what appear to be bacterial infections suggests that people were carrying out scientific studies centuries before bacteria were discovered.

Lee says the researchers now plan to try out other remedies from Bald’s Leechbook, including remedies for ulcers and headaches. Of course, they might do well to avoid some of the more colorful suggestions. According to one translation, Bald’s Leechbook proposes the following unusual–to say the least–“cure” for mental illness: “In case a man be a lunatic; take skin of a mereswine or porpoise, work it into a whip, swinge the man therewith, soon he will be well. Amen.”